https://en.wikipedia.org/wiki/Spectral_evidence was a form of legal evidence based upon the testimony of those who claim to have experienced visions.
Such testimony was frequently given during the witch trials of the 16th and 17th centuries. The alleged victims of witchcraft would claim to have been tormented by the spectral images of certain named members of the community; this was taken as evidence that those named were witches, and had given the Devil permission to assume their appearance.[1] If accepted by a court, this testimony was virtually impossible to refute.[2]
But there was a counter that held it back! Was it basic reasoning? No.
However, spectral evidence was rarely used to secure a conviction, as theologians were unable to agree that the Devil could not take on the shape of an innocent person.[3]